Epoxy resin adhesives are widely used for various purposes of electric, electronic, construction, automobile, aircraft and so forth because they can attain a high bonding strength and have excellent water resistance and heat resistance. In particular, one-part epoxy resin adhesives are used in the form of films, pastes or powders because they make it unnecessary to mix the base resin and the curing agent and can be used with ease. In this case, it is general to attain specific performances by using epoxy resins, curing agents and modifiers in various combinations (e.g., Japanese Patent Application Laid-open (KOKAI) No. 62-141083).
However, film type epoxy resin adhesives as disclosed in the above Japanese Patent Application Laid-open (KOKAI) No. 62-141083, though having an excellent operability, have been required to be heated at about 140 to 180° C. when connected in a time of about 20 seconds, and at about 180 to 210° C. when connected in 10 seconds.
This is because catalyst type curing agents, which are inert at normal temperature, are used so that both short-time curability (rapid curability) and storage stability (storability) can be achieved to attain a better stability, and hence no sufficient reaction can take place when cured.
In recent years, in the field of precision electronic equipment, circuits are being made higher in density, resulting in very small width of electrodes and very narrow spaces between electrodes. Hence, there has been a problem that the wiring comes off, separates or positionally deviates under connecting conditions for circuit-connecting materials making use of conventional epoxy resin adhesives. Also, in order to improve production efficiency, it is increasingly sought to shorten the connecting time to 10 seconds or less, making it indispensable to attain low-temperature rapid curability.